The art typically refers to systems for loading and unloading containers as “hook lifts.” These systems have been extensively employed for the transport of various materials within the container. In the usual case, the container may be loaded or unloaded upon the bed of the truck or vehicle utilizing the hook lift system. One very typical and frequent use for such systems is in the picking up and hauling of refuse. An open top or closed top container may be delivered to a point of use and the hook lift used to deploy the container, which contains a lift bar, A-frame or other similar connection to engage the hook, on the terrain underlying the truck where it is left to be filled with refuse or the like. When the container is full, the truck returns to the point where the container has been deposited and through the use of the hook lift system, elevates the filled container onto the truck where it may be transported, along with its contents, to a location where the container is unloaded and emptied, like a landfill or other facility. Examples of hook lift systems are found in U.S. Pat. Nos. 6,558,104; 5,601,393; 4,350,469; 3,874,537; 3,964,625; and 4,204,793.
In addition to hook lifts, the art is familiar with cable hoist systems which accomplish the same loading and unloading function of the hook lift systems but use a cable winch system as described in U.S. Pat. No. 5,460,473. In this type of a system two hydraulic cylinders are typically used to move the cable about a fixed sheave attached to the front end of the vehicle hoist frame. In the fully retracted position the cable, which is wrapped around sheaves connected to the cylinders, is at its longest affective length and can be connected to the front end of a container located on the ground. As the cylinders extend, the effective length of the cable continuously shortens as it wraps around each of the two cylinder sheaves and then finally around the sheave attached at the front end of the hoist frame. As the effective length of the cable gets shorter, the container is pulled up and onto the vehicle, which is usually in a tilted position to facilitate loading and unloading of the container. Another more limited and specific type of lift mechanism is found in U.S. Pat. No. 3,130,847 that uses a bail device mounted on a reciprocating carriage assembly. The bail engages a plurality of specifically designed hook bars located and space along the underneath portion of the container. As the carriage is reciprocated back and forth along a short path at the back end of the hoist frame the successive reciprocation causes the bail to engage the next hook bars and causing the container to move forward a short distance. The reciprocation of carriage eventually pulls the container onto the hoist frame in a slow stepwise fashion. One major problem with all these existing systems for loading and unloading containers is that they each contain only one type of mechanism to pick-up a specific type of container. For example, in the case of the hook lift it can only pick up containers designed specifically to accept the hook and likewise, the cable winch system can only pick up containers designed for cable based systems. Thus, companies must at a minimum maintain and operate two types of vehicles, those with hook lifts and those with cable winches. A need therefore exists for a universal type of loading and unloading system that can load, transport, and unload all types of containers, including, but not limited to those containers specifically designed for conventional cable hoists or hook lifts. In other words, there is a need for a system that has both a hook lift and a cable winch that can be used interchangeably depending on the many various designs of containers or other structures that require loading, transportation and unloading.
Our invention solves this problem by using a sliding carriage design that transverses the entire length of an elongated body to allow multiple types of container and structure designs to be loaded, transported on a wheeled vehicle and unloaded.